What is the difference between phase current and line current?

On a delta system the line current would be 1.732 times higher than the phase current. In a Wye system the line current and phase current are the same. In a parallel circuit (Delta) current divides. In a series circuit (Wye) current stays the same.

Another Answer

Line currents pass through line conductors, whereas phase currents pass through phases. 'Phases' are (in the case of a supply) are the windings of a three-phase alternator or (in the case of the load) are the loads themselves. 'Lines' are the three energised conductors that connect the load to the supply.